This invention relates to zinc borate as a smoke suppressant. More particularly, this invention relates to zinc borate as a smoke suppressant in high hydrocarbon content combustible silicone containing compositions.
The use of metal borates including zinc borate as smoke suppressants for PVC and other polyolefin materials has been reported in a number of publications and patents. Zinc borate is known to work well as a smoke suppressant when used either alone or in combination with antimony oxide for polymer compositions containing halogen, but is generally ineffective for non-halogen containing materials.
U.S. Pat. No. 4,182,799 discloses flame retardant additives for polystyrene foam. These additives comprise 40-56% by weight halogentated hydrocarbon, 14-22% by weight zinc borate, and 16-23% by weight Al(OH).sub.3.
Cowan, J.; Manley, T. R.; Br. Polym. J. 1976, 8(2), 44-7 disclose flame retardants and smoke suppressants for flexible PVC film. Ba and Ca borates with or without Sb.sub.2 O.sub.3 had little or no flame retardency, but Zn borate had a synergistic effect with Sb.sub.2 O.sub.3. Zn borate and Sb.sub.2 O.sub.3 were also found to be the most effective smoke suppressants.
Shen, Kelvin K., Sprague, Robert W.; J. Vinyl Technology 1982, 4(3), 120-3 disclose flame retardants and smoke suppressants for PVC. Zinc borate alone was found to be an effective flame retardant. Zinc borate in synergism with Al(OH).sub.3 was found to be an effective smoke suppressant.
Shen, Kelvin K.; Sprague, Robert W.; J. Fire Retardant Chemistry 1982, 9(3), 161-71 discloses flame retardants for epoxy resins. Zinc borate alone was found to be an ineffective flame retardant or smoke suppressant for epoxy resins in the absence of a halogen source.
It is the object of the present invention to utilize zinc borate as a flame retardant and smoke suppressant for certain silane containing compositions.
It is another object of the present invention to utilize zinc borate as a flame retardant and smoke suppressant for silicone containing compositions having high hydrocarbon content, particularly where the hydrocarbon content is in the form of aromatic rings.